A liquid crystal molecule cannot emit light by itself. Thus, a backlight module is employed in a liquid crystal display to provide a liquid crystal panel with a uniform and high-brightness light source. Generally, backlight modules may be categorized into side-edge backlight modules and direct-type backlight modules according to the distribution positions of light sources in the backlight modules. A light source in the side-edge backlight module is positioned at a side of a display panel, and the side-edge backlight module is usually used in a liquid crystal display of relatively small size. A light source in the direct-type backlight module is positioned at the bottom of a display panel, and the direct-type backlight module is usually used in a liquid crystal display of relatively large size.
An existing direct-type backlight module generally includes a backplane, a reflector and a light source which are arranged on the backplane, a diffuser arranged on the reflector, and a plastic frame which is arranged at the peripheries of the above components and is used for fixing the above components and a liquid crystal panel together. As compared with a side-edge backlight module, a direct-type backlight module has advantages of high light efficiency, no need of light guide plate, simple structure, and the like.
In the prior art, a light source includes a cold cathode fluorescent lamp (CCFL) and a light emitting diode (LED), and a through hole which corresponds to the position of the light-emitting body in a light source and enables the light-emitting body to pass through is previously provided on a reflector. When a direct-type backlight module and a liquid crystal panel are assembled, usually a light source is arranged on a backplane first, and then a reflector is arranged on the reflector. A through hole is provided on the reflector, and the light-emitting body in the light source passes through the through hole. A diffuser is arranged above the reflector. Then, the above components are assembled in a plastic frame to make the above components have fixed positions. Next, the liquid crystal panel is arranged above the plastic frame, and the backlight module and the liquid crystal panel are assembled together through the plastic frame. Finally, all of the above components are arranged into a casing.
In a backlight module, a plastic frame is used for ensuring the overall strength and the integrity of the backlight module, and is used for supporting a liquid crystal panel. From the aspect of structure, a plastic frame includes a one-piece plastic frame and a four-piece plastic frame (each piece thereof corresponds to one side of the liquid crystal panel). In the prior art, a mold for plastic frame is previously prepared, and then a plastic frame is formed by using polycarbonate (PC) material and by using the mold for plastic frame. The cost for manufacturing the mold for plastic frame and the cost of plastic frame material account for a large part of the cost of the backlight module. Especially in a backlight module of large size, the cost of a plastic frame makes the cost of a backlight module high.